package String;

public class StringBuilderDemo {
    public static void main(String[] args) {
        /*
        StringBuilder builder1 = new StringBuilder();
        StringBuilder builder2 = new StringBuilder("abc");
        String str = "abc";
        StringBuilder builder3 = new StringBuilder(str);
        String str2 = builder3.toString();
        */
        String str = "好好学习";
        StringBuilder builder = new StringBuilder(str);
        builder.append("，天天向上");
        System.out.println(builder);
        builder.replace(4,9,"，改变世界");
        System.out.println(builder);
        builder.delete(0,4);
        System.out.println(builder);
        builder.insert(0,"活着");
        System.out.println(builder);
    }
}
